<?php

if (! defined('BASEPATH'))
    exit('No direct script access allowed');

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package CodeIgniter
 * @author ExpressionEngine Dev Team
 * @copyright Copyright (c) 2006 - 2012 EllisLab, Inc.
 * @license http://codeigniter.com/user_guide/license.html
 * @link http://codeigniter.com
 * @since Version 2.0
 * @filesource
 *
 */
    
// ------------------------------------------------------------------------

/**
 * CodeIgniter Caching Class
 *
 * @package CodeIgniter
 * @subpackage Libraries
 * @category Core
 * @author ExpressionEngine Dev Team
 * @link
 *
 */
class CI_Cache extends CI_Driver_Library
{

    protected $valid_drivers = array(
            'cache_apc',
            'cache_file',
            'cache_memcached',
            'cache_dummy'
    );

    protected $_cache_path = NULL;
 // Path of cache files (if file-based cache)
    protected $_adapter = 'dummy';

    protected $_backup_driver;
    
    // ------------------------------------------------------------------------
    
    /**
     * Constructor
     *
     * @param
     *            array
     */
    public function __construct ($config = array())
    {
        if (! empty($config)) {
            $this->_initialize($config);
        }
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Get
     *
     * Look for a value in the cache. If it exists, return the data
     * if not, return FALSE
     *
     * @param
     *            string
     * @return mixed that is stored/FALSE on failure
     */
    public function get ($id)
    {
        return $this->{$this->_adapter}->get($id);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Cache Save
     *
     * @param
     *            string Unique Key
     * @param
     *            mixed Data to store
     * @param
     *            int Length of time (in seconds) to cache the data
     *            
     * @return boolean on success/false on failure
     */
    public function save ($id, $data, $ttl = 60)
    {
        return $this->{$this->_adapter}->save($id, $data, $ttl);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Delete from Cache
     *
     * @param
     *            mixed unique identifier of the item in the cache
     * @return boolean on success/false on failure
     */
    public function delete ($id)
    {
        return $this->{$this->_adapter}->delete($id);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Clean the cache
     *
     * @return boolean on failure/true on success
     */
    public function clean ()
    {
        return $this->{$this->_adapter}->clean();
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Cache Info
     *
     * @param
     *            string user/filehits
     * @return mixed on success, false on failure
     */
    public function cache_info ($type = 'user')
    {
        return $this->{$this->_adapter}->cache_info($type);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Get Cache Metadata
     *
     * @param
     *            mixed key to get cache metadata on
     * @return mixed value from child method
     */
    public function get_metadata ($id)
    {
        return $this->{$this->_adapter}->get_metadata($id);
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Initialize
     *
     * Initialize class properties based on the configuration array.
     *
     * @param
     *            array
     * @return void
     */
    private function _initialize ($config)
    {
        $default_config = array(
                'adapter',
                'memcached'
        );
        
        foreach ($default_config as $key) {
            if (isset($config[$key])) {
                $param = '_' . $key;
                
                $this->{$param} = $config[$key];
            }
        }
        
        if (isset($config['backup'])) {
            if (in_array('cache_' . $config['backup'], $this->valid_drivers)) {
                $this->_backup_driver = $config['backup'];
            }
        }
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * Is the requested driver supported in this environment?
     *
     * @param
     *            string The driver to test.
     * @return array
     */
    public function is_supported ($driver)
    {
        static $support = array();
        
        if (! isset($support[$driver])) {
            $support[$driver] = $this->{$driver}->is_supported();
        }
        
        return $support[$driver];
    }
    
    // ------------------------------------------------------------------------
    
    /**
     * __get()
     *
     * @param
     *            child
     * @return object
     */
    public function __get ($child)
    {
        $obj = parent::__get($child);
        
        if (! $this->is_supported($child)) {
            $this->_adapter = $this->_backup_driver;
        }
        
        return $obj;
    }
    
    // ------------------------------------------------------------------------
}
// End Class

/* End of file Cache.php */
/* Location: ./system/libraries/Cache/Cache.php */